1. Field of the Invention
This invention relates to antiplaque and antigingivitis effective oral compositions containing stabilized N.sup..alpha. -alkyl-L-arginine alkyl ester salts. The invention is also directed to a method for inhibiting plaque in the oral cavity.
2. Description of Related Art
It is known that dental plaque results from the adsorption and propagation of specific oral bacteria on the surface of the teeth. It is also known that the build up of dental plaque on the tooth surface is implicated in the formation of dental caries, as well as gingivitis and alveolar pyorrhea. Therefore, good oral health is critically dependent on the prevention or removal of dental plaque. Brushing the teeth is the most common means employed to reduce plaque build up. However, the effectiveness of brushing has limitations.
Various oral compositions have been formulated in an attempt to control plaque. For example, U.S. Pat. No. 5,266,306 describes an oral composition containing cetylpyridinium chloride as an antibacterial in combination with an N.sup..alpha. -cocoyl acyl basic amino acid lower alkyl ester or salt thereof that is said to promote adsorption of cetylpyridinium chloride. Exemplary adsorption promoters include N.sup..alpha. -cocoyI-L-arginine methyl ester hydrochloride, N.sup..alpha. -cocoyl-L-arginine methyl ester pyrrolidone carboxylate and N.sup..alpha. -cocoyl-L-arginine ethyl ester pyrrolidone carboxylate.
GB 1352420 describes lower alkyl esters of mono-N-higher aliphatic acyl arginine having the formula ##STR1## wherein RCO is a higher aliphatic acyl radical containing at least 6 carbon atoms and R.sup.1 is a lower alkyl radical containing up to 4 carbon atoms, or salts of the esters, that have antimicrobial or germicidal activity. In particular it is disclosed that N.sup..alpha. -cocoyl-L-arginine ethyl ester pyrrolidone carboxylate and N.sup..alpha. -cocoyl-L-arginine methyl ester pyrrolidone carboxylate provide bactericidal activity against Escherichia, Pseudomonas aeruginosa, Proteus vulgarus, Staphylococcus aureus, Bacillus substilis, Candida albicans and Aspergillus niger. It is further asserted that the arginine derivatives provided disinfectant activity against bacterium belonging to the genus Lactobacillus and Staphylococcus. However, this reference neither exemplifies a mouthwash composition nor suggests that the arginine derivatives would be effective against the specific bacterium associated with the formation of plaque.
Arginine esters have been employed in mouthwash compositions as surfactants. JP 04-005221 is directed to mouthwash compositions containing nonwater-soluble components, hydrophilic surfactants, ethanol and water. In particular, this publication describes a mouthwash composition containing vitamin E, N-cocoyl-L-arginine ethyl ester DL-pyrrolidone carboxylate, saccharin, flavor, ethanol and water that is diluted with additional water to give a homogeneous emulsion with an average particle size of 0.44 mm. Such an emulsion would be cloudy. However, mouthwash compositions that are cloudy are disadvantageous since consumers generally require clear single phase mouthwash compositions.
International Publication No. WO 93/11738 describes a dentifrice composition containing a bacteriocin (i.e. an antibacterial agent) such as nisin in combination with a cationic, amphoteric or nonionic surfactant. The D,L-2-pyrrolidone-5-carboxylic acid salt of ethyl-N-cocoyl L arginate is disclosed as a suitable surfactant. JP 57-165305 describes a method for improving the bacteriocidal effect of surfactant type disinfectants such as chlorohexidine digluconate by the addition of N.sup..alpha. -cocoyl-L-arginine ethyl ester DL-pyrrolidine carboxylate. The arginine ester is said to have weak bacteriocidal activity, but brings about a synergistic improvement in the bacteriocidal effect of the surfactant type disinfectants.
Ethyl N.sup..alpha. -cocoyl-L-arginate pyrrolidone-5-carboxylic acid salt, sold under the tradename CAE.RTM., ethyl N.sup..alpha. -lauryl-L-arginate pyrrolidone-5-carboxylic acid salt (hereinafter "LAE") and iso-propyl N.sup..alpha. -lauryl-L-arginate pyrrolidone-5-carboxylic acid salt (hereinafter "LAIP") are available from Ajinomoto Co., Inc., Tokyo, Japan. They are said to be useful as disinfectants or bactericidally active ingredients. There is, however, no suggestion or disclosure in the prior art that N.sup..alpha. -acyl amino acid ester salts would be effective against the specific microorganisms associated with plaque buildup.
However, aqueous compositions containing salts of N.sup..alpha.- alkyl-L-arginine alkyl esters generally undergo hydrolysis reactions typical of esters. Thus, an antiplaque and antigingivitis effective oral composition that contained a stabilized N.sup..alpha. -acyl amino acid ester salt would be highly desirable.